Look at it this way, You'll be 59 before you can retire in the military.. Do you really think you're going to handle twenty years of it? You're going to have 19 and 20 year olds in charge of you, even your higher ups (Staff NCOs, Officers..) will be younger than you. You will not be treated special because you are older.. You will be expected to do the shit jobs that 18 year old privates straight out of high school have to do. Granted..
The Army as a whole is "Older" than the Marine Corps (Where I was) but it will still be very similar... Hell we had 26 year olds in boot camp with us and they where older than most of our Drill Instructors... lol